Just read this article 'Biting the Bullet' in BT dated 27th Nov 2011. Sharing the most interesting bit:
But the new engine, unlike the old, had hydraulic tappets, a new engine arrangement, new metal and fewer moving parts. Obviously it did not produce the vibrations and the beat of the old, but international experts were consulted and sound mapping carried out for over 1,000 hours to ensure it produced maximum rhythmic vibrations possible and a beat, which was 70 per cent of the amplitude of the original.It further says:
After much testing, the silencer was extended to capture, to the extent possible, the throb of the old engine.Now that's how we sustain a brand. Great job! Innovation in mechanics to please the senses in the same old ways. Lovely.